Fait général: 1389 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fait mathématique: 1389 is the number of unit interval graphs with 9 vertices.
Culture générale: 1389 is an unremarkable number.
Date historique: October 20th is the day in 1910 that the hull of the RMS Olympic, sister-ship to the ill-fated RMS Titanic, is launched from the Harland and Wolff shipyard in Belfast, Northern Ireland.